Skip to main content
padlock icon - secure page this page is secure

Shoemaker impact structure, Western Australia

Buy Article:

$61.00 + tax (Refund Policy)

The Shoemaker impact structure, on the southern margin of the Palaeoproterozoic Earaheedy Basin, with an outer diameter of ∼30 km, consists of two well‐defined concentric ring structures surrounding a granitoid basement uplift. The concentric structures, including a ring syncline and a ring anticline, formed in sedimentary rocks of the Earaheedy Group. In addition, aeromagnetic and geological field observations suggest that Shoemaker is a deeply eroded structure. The central 12 km‐diameter uplift consists of fractured Archaean basement granitoids of syenitic composition (Teague Granite). Shock‐metamorphic features include shatter cones in sedimentary rocks and planar deformation features in quartz crystals of the Teague Granite. Universal‐stage analysis of 51 sets of planar deformation features in 18 quartz grains indicate dominance of sets parallel to ω {1013}, but absence of sets parallel to π {1012}, implying peak shock pressures in the range of 10–20 GPa for the analysed sample. Geophysical characteristics of the structure include a —100 μs ‐2 gravity anomaly coincident with the central uplift and positive circular trends in both magnetic and gravity correlating with the inner ring syncline and outer ring anticline. The Teague Granite is dominated by albite‐quartz‐K‐feldspar with subordinate amounts of alkali pyroxene. The alkali‐rich syenitic composition suggests it could either represent a member of the Late Archaean plutonic suite or the product of alkali metasomatism related to impact‐generated hydrothermal activity. In places, the Teague Granite exhibits partial to pervasive silicification and contains hydrothermal minerals, including amphibole, garnet, sericite and prehnite. Recent isotopic age studies of the Teague Granite suggest an older age limit of ca 1300 Ma (Ar–Ar on K‐feldspar) and a younger age limit of ca 568 Ma (K–Ar on illite‐smectite).The significance of the K–Ar age of 568 Ma is not clear, and it might represent either hydrothermal activity triggered by impact‐related energy or a possible resetting by tectonothermal events in the region.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Article Media
No Metrics

Keywords: Earaheedy Basin; Teague Granite; aeromagnetics; alkali metasomatism; gravity; impact structure; shatter cones

Document Type: Research Article

Affiliations: 1: Geological Survey of Western Australia, 100 Plain Street, East Perth, WA 6004, Australia 2: School of Earth and Geographical Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia 3: Research School of Earth Sciences, Australian National University, ACT 0200, Australia 4: School of Earth Sciences, University of Tasmania, Tas. 7005, Australia 5: Department of Earth Sciences, University of Queensland, Qld 4072, Australia

Publication date: October 1, 2003

  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more